Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

69c0093e42be9a53221571e7a251526d36e53c74d382ceb8eb1749e67c619885

Seed

8d8f817a08144aa7008d232fcd77aecd9019e193ab407a9e42e0d929064a425c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b73f8992c669bd1f2c097cdd300074cb

Commitment

Batch 48,095, Merkle root 1195ee7d7183f5aa51cddb015e3828df179d8aa7ecc0faff60d79529839458ec. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 22b1df1cc44df9be672c81724cc0c7002f477170b2e1f455c1932cab1946df15
2. d6a81107ace856515b0aa038e8184ecd5579639e278f10eb99f56af2c412a2f1

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.